(1) Field of the Invention
The present invention pertains to a motor shaft bearing assembly in which a self-aligning bearing supports the motor shaft in a bearing seat to allow pivoting movement of the motor shaft relative to bearing seat during motor assembly. In addition, the bearing assembly includes a projection adjacent the bearing seat that engages into an end face of the bearing to restrict the movement of the bearing relative to the bearing seat. As an alternative or in addition to the projection adjacent the bearing seat, a bearing retainer holding the bearing against the bearing seat is provided with a projection that engages into the exterior surface of the bearing to restrict the movement of the bearing relative to the bearing seat.
(2) Description of the Related Art
Various different types of bearing assemblies have been employed in mounting rotating shafts to a supporting structure. For example, in the construction of electric motors, bearing assemblies employing ball bearings, roller bearings, babbitt bearings, and self-aligning bearings have been used in supporting the rotating shaft of the electric motor in an end shield of the motor.
Of the above-mentioned different types of bearing assemblies, the bearing assembly employing a self-aligning bearing is typically more cost efficient than the other types of bearing assemblies. This is primarily because the use of ball bearing, roller bearing or babbitt bearing assemblies requires expensive machining steps to be performed on the motor end shield before the bearing assembly can be mounted in the end shield.
The self-aligning bearing is typically constructed of sintered metal. The bearing is formed with a generally spherical exterior surface and a pair of flat, axially opposite end face surfaces. A shaft center bore passes through the bearing between the end face surfaces.
In mounting the bearing on a motor end shield, the bearing is positioned on a bearing seating surface that has been inexpensively cast on the motor end shield. A bearing retainer having resilient fingers or tabs is assembled to the end shield. The bearing retainer tabs engage against and urge the bearing against the bearing seat of the end shield. The motor shaft can then be inserted through the bearing center bore. The construction of the self-aligning bearing permits the motor shaft and the bearing to pivot or swivel relative to the end shield bearing seat as the motor is assembled.
However, there are certain situations in which the swiveling or pivoting movement of the self-aligning bearing relative to the motor end shield bearing seat is undesirable. Many small horsepower motors are assembled by bonding the motor's stator between a pair of motor end shields. An epoxy is often used as the adhesive. After assembly of the motor component parts between the end shields, the component parts must not move relative to each other as the epoxy cures. The ability of the self-aligning bearing to pivot or swivel relative to the end shield bearing seat will at times allow the motor shaft to move relative to the end shield before the epoxy is fully cured. This can result in defects in the motor construction. For example, movement of the motor shaft can cause a cooling fan mounted on the motor shaft to come into contact with a portion of the adjacent end shield.
To overcome the above disadvantage of self-aligning bearing assemblies used in the construction of electric motors, a restraining force could be used on the bearing to hold the self-aligning bearing stationary against the bearing seat. However, because most self-aligning bearings are sintered bearings, increasing the force on the bearing exterior to hold the bearing stationary against the end shield bearing seat could deform the interior shaft bore of the bearing.